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Record 21 of 2371
Experimentation Toward the Analysis of Gear Noise Sources Controlled by Sliding Friction and Surface Roughness
Author and Affiliation:
Asnani, Vivake M.(Ohio State Univ., Electrical and Computer Engineering, OH, United States)
Abstract: In helicopters and other rotorcraft, the gearbox is a major source of noise and vibration (N&V). The two N&V excitation mechanisms are the relative displacements between mating gears (transmission errors) and the friction associated with sliding between gear teeth. Historically, transmission errors have been minimized via improved manufacturing accuracies and tooth modifications. Yet, at high torque loads, noise levels are still relatively high though transmission errors might be somewhat minimal. This suggests that sliding friction is indeed a dominant noise source for high power density rotorcraft gearboxes. In reality, friction source mechanism is associated with surface roughness, lubrication regime properties, time-varying friction forces/torques and gear-mesh interface dynamics. Currently, the nature of these mechanisms is not well understood, while there is a definite need for analytical tools that incorporate sliding resistance and surface roughness, and predict their effects on the vibro- acoustic behavior of gears. Toward this end, an experiment was conducted to collect sound and vibration data on the NASA Glenn Gear-Noise Rig. Three iterations of the experiment were accomplished: Iteration 1 tested a baseline set of gears to establish a benchmark. Iteration 2 used a gear-set with low surface asperities to reduce the sliding friction excitation. Iteration 3 incorporated low viscosity oil with the baseline set of gears to examine the effect of lubrication. The results from this experiment will contribute to a two year project in collaboration with the Ohio State University to develop the necessary mathematical and computer models for analyzing geared systems and explain key physical phenomena seen in experiments. Given the importance of sliding friction in the gear dynamic and vibro-acoustic behavior of rotorcraft gearboxes, there is considerable potential for research & developmental activities. Better models and understanding will lead to quiet and reliable gear designs, as well as the selection of optimal manufacturing processes.
Publication Date: Jan 01, 2004
Document ID:
20050186648
(Acquired Jul 12, 2005)
Subject Category: ACOUSTICS
Document Type: Conference Paper
Publication Information: Research Symposium II; (SEE 20050186580)
Meeting Sponsor: NASA Glenn Research Center; Cleveland, OH, United States
Financial Sponsor: Ohio State Univ.; Electrical and Computer Engineering; OH, United States
Organization Source: Ohio State Univ.; Electrical and Computer Engineering; OH, United States
Description: In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: No Copyright
NASA Terms: NOISE INTENSITY; GEARS; FRICTION REDUCTION; NOISE GENERATORS; SLIDING FRICTION; HELICOPTERS; TRANSMISSIONS (MACHINE ELEMENTS); MATHEMATICAL MODELS
Availability Notes: Abstract Only; Available from STI Support Services only as part of the entire parent document
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